A resin foam may be bonded as a protection layer to a surface on a radiation element side of an array antenna formed of a dielectric material. The resin foam also provides advantages such as thinning of the antenna device, suppression of antenna gain reduction, and mechanical strength enhancement.
On the other hand, a surface of a radome of an antenna device is warmed to melt snow sticking to the radome in snowy regions. However, there is a problem that no sufficient snow melting effect can be obtained in an antenna device with a resin foam bonded thereto even if the radome is warmed because of a heat insulation effect of the resin foam. Therefore, contrivances for enhancement in warming capability have been studied, but antenna characteristics are often lost by such contrivances.